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Friday, December 1, 2023

Shucking Oysters: Marine Heatwaves…tearing me apart

Shucking Oysters: Marine Heatwaves…tearing me apart

Alex Allen

There seems to be a pattern here. We read and hear about some horrible or surreal event  elsewhere in the world and then just like that, it happens in our “world” too. Thankfully, the United States has held off attacking Canada. But, with their insecurities and love for the absurd and vulgar, you just never know. 

Wildfires. Floods. Drought. Heatwaves. It shows how interconnected we all are in this world. If a tree burns in Tenerife, the world will not only hear it, they will feel it. 

Now we have marine heatwaves. In July, water off the tip of Florida reached 39°C (101°F)! To put it into perspective, a comfortable soak in a hot tub is 101°F, the optimum temperature. Above 104°F can lead to heatstroke. 

Coral bleaching. Marine mammal die offs. It’s like someone keeps turning the climate knob higher and higher.

And then in August, just like that, a marine heatwave hit the BC coast, bringing with it temperatures five degrees warmer than normal. It started in the waters off California in May, then grew to an area covering about four million sq. km. (twice the size of Alaska), before moving towards Oregon, Washington and BC coasts. This not a new event, apparently. Heatwaves form offshore in the Pacific every spring and grow early summer. The difference, is that they don’t always reach the coast. And that’s the scary situation.

Warmer ocean temperatures can affect every living thing in the ocean, from the smallest phytoplankton to marine mammals. Some species are directly affected by heat, becoming stressed, while others experience a loss of food, because the animals they eat are dying, warned Julia Baum, biology professor at the University of Victoria. It can also lead to more marine mammals getting caught in fishing nets or hit by ships while they’re migrating along the coast, with the narrowing travel corridor of cool water, pushing them closer and closer to shore. Read the news lately? 

In June, field teams near Denman Island studying long-term change in kelp forests noticed “extremely warm” waters, measuring 21°C, Baum said, when the historical average summer water temperature is about 14°C to 15°C.

Fish that prefer cold water, like cod and salmon, are particularly vulnerable to heatwaves. Warm water forces them to work harder, which means they need more food to sustain themselves. At the same time, it can make prey less accessible — keeping the zooplankton from rising to the surface.

In 2021, BC closed 60% of its commercial Pacific salmon harvests. As many as 30 million sockeye salmon migrated up British Columbia’s Fraser River in 2010. A decade later, only 291,000 salmon returned. The fish are declining for a number of reasons, but studies say extreme ocean heat is a major culprit. 

Scientists predict more fisheries will collapse in the coming years as climate change — and the ongoing El Niño weather pattern warming the Pacific — causes more marine heatwaves. “I’m really worried,” said William Cheung, director of the Institute of Oceans and Fisheries at UBC. “This year we already know the temperature is crazy high.” 

Conditions are not yet as dire as they were in 2014 and 2015, when a huge marine heatwave, affectionately titled, the Blob, took hold in the Pacific, leading to seabird die-offs, record numbers of whales caught in fishing lines, starving sea lion pups washing up on beaches and plummeting salmon returns. With forecasts showing El Niño looming next winter, a worst case scenario could see the heatwave sticking around and rolling into warm El Niño conditions, which could lead to a similar situation. 

The Blob was first spotted in the Gulf of Alaska and grew and grew until it covered an area about the size of continental United States. But as Max Graham wrote in the Grist, you could have easily missed it. “A heat wave in the ocean is not like one on land. What happens on the 70% of the planet covered by saltwater is mostly out of sight. There’s no melting asphalt, no straining electrical grids, no sweating through shirts. Just a deep-red splotch on a scientist’s map telling everyone it’s hot out there, and perhaps a photo of birds washed up on a faraway beach to prove it.” 

Like “canaries in the coal mine,” dying seabirds are often the first alarm bell of a struggling ecosystem. Their deaths are considered a warning sign of how warming temperatures are affecting the environment as a whole. 

Birds Canada’s David Bradley and other BC scientists were part of a eye-opening study released in July by the University of Washington. Eye-opening because it is the first study that shows a clear link between bird mortality and marine heatwaves. The group examined 90,000 seabird deaths along 500 km of the Pacific coast and discovered five massive die-off events between 2014 and 2019. They caution that ocean warming is indirectly causing mass mortality among seabirds, not directly. “The exact cause of each die-off is different, but all seem to be related to warmer waters … thus affecting the whole marine ecosystem.” It could be algae blooms, increased disease outbreaks, or changes in the quality and abundance of prey, which can lead to starvation. After the 2021 heat dome that hit the province, a UBC scientist found that over a billion seashore animals likely died as shoreline temperatures reached 50°C.

Birds Canada is looking for volunteers. If you want to participate in the Birds Canada “Beached Bird Survey” [say that quickly], you can become a coastal guardian by contacting Rémi Torrenta at: rtorrenta@birdscanada.org. You will identify and tag the dead seabirds you encounter. Go to their website or email: bcvolunteer@birdscanada.org to get your free tool kit. The concept is simple and anyone can take part: simply walk your favourite beach every month to report and identify all the bird carcasses you found, or the absence of. Happy beachcombing! 

Author: TIG

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